A federal judge took the unusual step yesterday of tripling the suggested sentence for a Somali community leader convicted of immigration crimes, saying the harsher sentence was justified because of national security concerns.

After Omar Abdi Mohamed declined to make a statement to the court, U.S. District Judge John Houston sentenced the self-described Muslim missionary to 18 months in prison. Mohamed has already served two years while awaiting the outcome of his case....

Mohamed, 45, was never charged with terrorism. He was convicted in two trials of six felony charges that he lied on visa and naturalization applications. He was acquitted of more serious charges, particularly that he lied during a citizenship interview about his association with the two charities in question, Global Relief Foundation and the Al-Haramain, which the U.S. government has linked to terrorist fundraising.

In explaining his departure from the sentencing guidelines, which suggest a six-month sentence, Houston said he was not focusing on whether Mohamed lied, but on the undisputed facts of the case. He said he found sufficient evidence that Mohamed received $300,000 from those terror-linked charities, regardless of whether he lied about it. "He was acquitted of lying about the receipt of money, but the evidence was clear that he received the money," Houston said. "In my mind, I can consider the receipt of money as affecting national security."